Turkey: Who is Fethullah Gulen, President Recep Tayyip Erdogan's enemy?

Islamic cleric Fethullah Gulen is pictured at his residence in Saylorsburg, PennsylvaniaReuters

Turkish authorities have issued an arrest warrant for an influential opponent of President Recep Tayyip Erdogan days after seizing control of media sympathetic to his cause. Prosecutors in the eastern city of Erzurum said Fethullah Gulen and his brother Salih are wanted on a series of charges including participating in a terrorist organisation and violating the constitution.

The move came amid an intensifying feud between Erdogan and his former ally, who lives in the US and is accused of running a parallel state aiming to topple the government. Two newspapers and a news agency affiliated to Gulen's Hizmet (service) movement have been seized by the courts over the past few days.

The publications included Zaman, Turkey's largest circulation newspaper, which coverage turned from critical to supportive of the government overnight after the takeover. The arrest warrant was issued after police searched a printing house owned by Salih Gulen for documents allegedly detailing subversive activities, prosecutors said in a statement.

It was not the first time authorities ordered Gulen be captured. The 75-year-old has lived in self-imposed exile in Pennsylvania since 1999, when he was first accused of plotting to overthrow the government.

The allegation stemmed from a video recording in which Gulen urged his followers to secretly gather as much power as they could by infiltrating and moving up the state system until they took over control of the country's constitutional institution. The cleric maintained the tape had tampered with and was later acquitted in absentia.

Back then, the Gulen movement was on good terms with Ergogan's AKP party, as both groups advocated a moderate version of Islam that put them at loggerheads with the secular government and the military. Hizmet, which counts on an impressive network of more than 1,000 schools in 140 countries, from South Africa to the United States and exerted extensive influence in the media, police and judicial system, provided indispensable support for Erdogan to win his first elections in 2002.

The organisation has often been defined has secretive or opaque due to its lack of formal structure and Gulen's own secrecy. The imam rarely concedes interviews and lives a retired life in his estate in Saylorsburg.

Due to Hizmet's wide reach, the charismatic imam was nevertheless once described as Turkey's second most powerful man. He wielded authority over a large number of media and businesses that although not directly owned or controlled by him were led by members of his social religious network.

In recent years Gulen's sway has been significantly dented by his rift with the increasingly authoritarian president that led to a series of arrests and the takeover of companies linked to the cleric. The clampdown reached its epitome with the seizing of Zaman.

"Zaman was the landmark media outlet of the Gulen movement," said Ege Seçkin, an analyst at IHS. The newspaper was the top selling daily in Turkey, with a circulation of about 650,000, almost double that of the runner-up, the liberal Hurriyet.

On 4 March after a court appointed trustees to replace the paper's management police raided its premises firing teargas on protesters that had gathered outside. Journalists said authorities tried to wipe out the newspaper archive and cut off internet to prevent them publish non-vetted content.

The editor-in-chief Abdulhamit Bilici and a prominent columnist were fired, as other reporters were forced to work "under police surveillance", according to Sevgi Akarcesme, the editor of the sister English-language publication Today's Zaman. The first issue of the newspaper published under the new leadership opened with articles praising Erdogan over the construction of a third bridge across the Bosphorus.

The idyll between Erdogan and Gulen began to crumble over their different views on the peace process with Kurdish separatists and peaked in 2013, with a massive corruption scandal that the government said was orchestrated by the Hizmet movement to topple it.

The movement has since been branded a terrorist organisation, despite no evidence of its involvement in violent actions, and many of its affiliates have been purged or indicted. Gulen himself has been put on trial in absentia, although the US has shown no sign of wanting to extradite him.

Meanwhile analysts say the takeover of Zaman however is also symptomatic of a wider crackdown on opposition. Seçkin said the government is under increasing pressure as it faces crisis at home, with refuses from the corruption scandal adding to a revival of the violent Kurdish insurgency in the south-east and the spill overs from the conflict in neighbouring Syria.

"To maintain the dominant support of population they should have control of the public discourse," he said Seçkin adding that silencing media opposition might also prelude to a new attempt from Erdogan to extend his powers by changing the constitution.